Lifting-jack.



J. B. SMYTHE.

I LIFTING JACK.

APPLICATION FILED 0OT.26,1912.

2 SHEETSSHEET 1.

1,079,371. Patehted Nov. 25; 1913.

Inventor:

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LIPTING JACK. APPEIOATION IILED 001'. 26, 1912 Patented Nov. 25, 1913.

2 SHEETS-SHEET 2.

Irwenior: I0sephB.Sm yHw JOSEPH B. SMYTHE, OF COATICOOK, QUEBEC, CANADA.

LIFTING-J'AGK.

Specification of Letters Patent.

Application filed. October 26, 1912.

Patented Nov. 25, 1913. Serial No. 728,262.

To all whom it may concern:

Be it known that I, J osErH B. SMYTHE, a subject of the Dominion of Canada, and a resident of Coaticook, Province of Quebec,

i Canada, have invented certain new and useful Improvements in Lifting- Jacks, of which the following is a specification.

This invention relates to lifting jacks and particularly to that form of jacks which are known as ratchet screw jacks, and has for its object the provision of means whereby the lowering of the movable member may be controlled manually.

The invention consists in providing the jack with a ratchet adapted to be rotated by the reverse movement of the devices for raising the movable member and controlling this rotation of said ratchet by means of two pawls alternately adapted to engage the teeth of the ratchet, thereby permitting said ratchet to rotate intermittently.

The invention further consists of an oscillating member for imparting movement to said pawls and a crank for operating said oscillating member.

The invention further consists in certain novel features of construction and arrangement of parts which will be readily understood by reference to the description of the drawings and to the claims hereinafter given.

Of the drawings: Figure 1 represents a vertical section of a jack embodying the features of the present invention. Fig. 2 represents a vertical section of a portion of the same, showing the devices for controlling the lowering of the movable member. Fig. 3 represents an elevation of the upper portion of the jack, and Fig. 4 represents an elevation of the devices for controlling the lowering of the movable member.

Similar characters designate like parts throughout the several figures of the drawings.

In the drawings, 10 represents a suitable base supporting a stationary standard 11, over the outer periphery of which is fitted a movable sleeve 12 to the upper end of which is threaded a cap 13. In the upper end of the standard 11 is mounted a nut 14 to which is threaded a lifting screw 15 having splined to its upper reduced end a gear 16 with which meshes the gear 17 formed upon or secured to a revoluble shaft 18. The outer end is provided with a suitable operating mechanism 19 of any well known construction. Interposed between the upper face of the gear 16 and the wall of the cap 13 are two annular plates 20 and 21 between which are interposed a plurality of antifriction members 22. On the spindle 18 and secured thereto is a ratchet wheel 23, which is surrounded by a gear 24 having mounted therein the pawls 25 adapted to engage the teeth of the ratchet wheel 23 when the movable member 12 is lowered and move said ratchet wheel in the direction of the arrow at on Fig. 4 of the drawings. This gear 24 meshes with the pinion 26 having a spindle 27 extending through the closing plate 28 secured by means of the screws 29 to the flanges 30 formed upon the movable member 12. Keyed to the spindle 27 and revoluble therewith is a ratchet wheel 31 adapted to move in the direction of the arrow 72 on Fig. 4 of the drawings when the movable member 12 is lowered. The closing plate 28.

has extending therethrough the spindle 32 of an oscillating member 33, said spindle being intermediate the ends of said member 33, the outer ends of which are forked and have pivoted thereto at 34 and 35 the pawl members 36 and 37. The outer pawl member 36 is normally in engagement wit-h one of the teeth of the ratchet 31, thereby preventing its movement in the direction of the arrow 6, thus resisting any tendency of the movable member 12 tolower under its load.

Secured to the outer end of the spindle 32 is a lever 38 provided with a slot 39 therein extending lengthwise thereof. In the slot 39 is positioned the cylindrical stud 40 formed upon or secured to a crank arm 41 provided with a spindle 42 extending through a bearing in the closing plate 28 in which it is free to revolve. The outer end 43 of the stud 40 is squared and adapted to receive the handle 44. When it is desired to lower the movable member 12 under its load the operator by means of the handle 44 may turn the crank 41 about the axis of its spindle 42, thereby producing through the medium of the slotted lever 38 an oscillation of the member 33. As this member 33 oscillatesand the pivot pin 34 moves upwardly it will permit the extreme end'of the pawl 36 to ride over one of the teeth of the ratchet wheel 31, the downward movement of the pawl 37 during the oscillation of the member 33 tending to force said pawl 36 outwardly from the path of the teeth of said ratchet wheel 31. As the pawl 37 moves downwardly it will clear the point of one of the teeth of the ratchet wheel 31 and then be forced inwardly, by means of the cam portion 45 on the pawl 36, into the path of the nexttooth, thereby retarding the movement of the ratchet 81 until a complete oscillation of the member 33 has been completed and the extreme lower end of the pawl 36 has passed over one tooth into position to engage the next. The plate 28 provided with a lug 46 which limits the outward movement of the pawl 36, which pawl is provided with a cam surface 47 at its extreme upper end coacting with the fixed pin or stud 48 to regulate the movement of the said pawl 36 during the oscillation of the member The upper end of the pawl 36 is provided with a spring 49 which tends to keep the cam surface 4? in contact with the periphery of said pin 48. The upper end of the pawl 37 is also provided with a spring 50 engaging a fixed stud or pin 51, thereby retaining the opposite end of said pawl in'contact at all times with the inner wall of the pawl 36. It is obvious that when the crank 41 is in the position indicated in Fig. 3 of the drawings, the pawls 36 and 37 are retained in the position shown in Fig. 4 of the drawings, said pawl 36 thereby preventing any movement of the ratchet wheel 31 in the direction 01 the arrow Z) and consequently preventing the lowering of the movable member 12. As soon, however, as it is desired to lower the said movable member 12, the operator may, by means of the handle 44, rotate the crank 41, and by oscillating the member 33 secure an intermittent rotation of the ratchet wheel 31 and consequently the gears 24, thereby permitting the slow lowering of the movable member. The lowering of the movable member may be re ulated to any desired speed by varying the speed of rotation of the handle 44. This makes a very effective means for controlling the lowering of the jack, and is very positive in its operation.

It is believed that the operation and many advantages of thisinvention will be fully understood from the foregoing description.

Having thus described my invention, I claim:

1. In a device of the class described, the combination of a stationary member; a movable member thereon; a revoluble member for raising said movable member; means for rotating said revoluble member to raise said movable member; a ratchet wheel inoperative during the raising operation but adapted to be rotated by the reverse movement of said revoluble member; and mechanism including a manually controlled crank normally engaging said ratchet to prevent the lowering of said movable member but adapted to be released therefrom to permit an intermittent movement of said ratchet and a gradual lowering of said movable member during the rotation of said crank.

In a device of the class described, the combination of a stationary member; a movable member thereon: a rcvolublc member for raising said movable member; means For rotating said revolublc member; a ratchet wheel lllODOl'tlt-lVO during the raising operation but adapted to be rotated by the reverse movement of said rcvoluble member; a crank; a member adapted to be oscillated by the rotation of said crank; and means controlled by the oscillation of said member normally engaging the teeth of said ratchet wheel to prevent the lowering of said movable member but adapted to be released therefrom to permit an intermittent movement of said ratchet and a gradual lowering of the movable member during the rotation of said crank.

In a device of the class described, the combination or a stationary member; a movable member thereon; a revoluble member for raising said movable member; means for rotating said revoluble member; a ratchet wheel inoperative during the raising operation but adapted to be rotated by the reverse movement of said revoluble member; a crank; a pivoted member provided with a slot engaged by said crank and adapted to be oscillated by the rotation thereof: and mechanism secured to the pivot of said oscillating member and normally engaging said ratchet wheel to prevent the eri of said movable member but adapted to be released therefrom to permit an intermittent movement of said ratchet and a gradual lowering of said movable member during the rotation of said crank.

Signed by me at 4 Post Oiiice Square, Boston, Mass, this 11th day of October, 1912.

JOSEPH B. SMYTHE.

Witnesses:

VALTER E. LOMBARD, NATHAN O. LOMBARD.

Copies of this patent may he obtained for five cents each, by addressing the Commissioner of latents,

' Washington. D. C. 

